A Blockchain-Based Collaborative Auditing Scheme for Cloud Storage

Cloud storage system has brought great convenience but also brings serious security problems. To ensure data security in the cloud, users usually authorize a third-party auditor (TPA) to verify their data integrity regularly. However, TPA may lead to security threats such as data disclosure and tampering. Fortunately, blockchain makes up for the lack of TPA. But there exists the problem of interaction difficulties and expensive deployment of smart contracts in the blockchain scenario. This paper proposes a blockchain-based collaborative public auditing scheme for remote data. In the proposed scheme, the cloud service provider (CSP) completes the challenge and verification work independently, reducing the communication overhead in the proof stage and improving the overall system efficiency. In addition, we consider allowing users to seek partners to reduce the cost of personal audits. Through the EigenTrust model evaluating the credibility of users, the users can select a high-quality partner to complete public auditing work, effectively avoiding collusion among malicious users. The proposed scheme can be proved secure and efficient according to the complete security analysis and comprehensive performance evaluation.